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Zou GY, Wen Y, Bi F, Chen S, Yu YL, Wang JH. A "dual-key-and-lock" ratiometric fluorescent probe with biocompatibility and selectivity for imaging vicinal dithiol proteins. Chem Commun (Camb) 2023; 59:1785-1788. [PMID: 36722873 DOI: 10.1039/d2cc06422g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
TMR-TPE, a ratiometric fluorescent probe, was reported for the imaging of vicinal dithiol proteins (VDPs) in living cells. Profiting from the "dual-key-and-lock" design, TMR-TPE solves the toxicity problem of VDP probes (98% cell viability at 50 μM) and avoids the interference of small thiols (up to 10 mM GSH). The change of VDPs during drug-induced liver injury was monitored for the first time using TMR-TPE.
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Affiliation(s)
- Guang-Yue Zou
- Research Center for Analytical Sciences, Department of Chemistry, College of Sciences, Northeastern University, Box 332, Shenyang 110819, China.
| | - Yun Wen
- Research Center for Analytical Sciences, Department of Chemistry, College of Sciences, Northeastern University, Box 332, Shenyang 110819, China.
| | - Fan Bi
- Research Center for Analytical Sciences, Department of Chemistry, College of Sciences, Northeastern University, Box 332, Shenyang 110819, China.
| | - Shuai Chen
- Research Center for Analytical Sciences, Department of Chemistry, College of Sciences, Northeastern University, Box 332, Shenyang 110819, China.
| | - Yong-Liang Yu
- Research Center for Analytical Sciences, Department of Chemistry, College of Sciences, Northeastern University, Box 332, Shenyang 110819, China.
| | - Jian-Hua Wang
- Research Center for Analytical Sciences, Department of Chemistry, College of Sciences, Northeastern University, Box 332, Shenyang 110819, China.
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2
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An Activatable T 1-Weighted MR Contrast Agent: A Noninvasive Tool for Tracking the Vicinal Thiol Motif of Thioredoxin in Live Cells. Molecules 2021; 26:molecules26072018. [PMID: 33916181 PMCID: PMC8037249 DOI: 10.3390/molecules26072018] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2021] [Revised: 03/20/2021] [Accepted: 03/22/2021] [Indexed: 12/20/2022] Open
Abstract
We have synthesized new magnetic resonance imaging (MRI) T1 contrast agents (CA1 and CA2) that permit the activatable recognition of the cellular vicinal thiol motifs of the protein thioredoxin. The contrast agents showed MR relaxivities typical of gadolinium complexes with a single water molecule coordinated to a Gd3+ center (i.e., ~4.54 mM−1s−1) for both CA1 and CA2 at 60 MHz. The contrast agent CA1 showed a ~140% relaxivity enhancement in the presence of thioredoxin, a finding attributed to a reduction in the flexibility of the molecule after binding to thioredoxin. Support for this rationale, as opposed to one based on preferential binding, came from 1H-15N-HSQC NMR spectral studies; these revealed that the binding affinities toward thioredoxin were almost the same for both CA1 and CA2. In the case of CA1, T1-weighted phantom images of cancer cells (MCF-7, A549) could be generated based on the expression of thioredoxin. We further confirmed thioredoxin expression-dependent changes in the T1-weighted contrast via knockdown of the expression of the thioredoxin using siRNA-transfected MCF-7 cells. The nontoxic nature of CA1, coupled with its relaxivity features, leads us to suggest that it constitutes a first-in-class MRI T1 contrast agent that allows for the facile and noninvasive monitoring of vicinal thiol protein motif expression in live cells.
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Wei X, Jin T, Huang C, Jia N, Zhu W, Xu Y, Qian X. Monoarsenical-based chemical approaches for exploration of endogenous vicinal-dithiol-containing proteins (VDPs): From the design to their biological application. Coord Chem Rev 2021. [DOI: 10.1016/j.ccr.2020.213621] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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4
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Affiliation(s)
- Robert E Click
- Altick Associates, 2000 Maxwell Drive, Hudson, WI 54016, USA
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5
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Zhang R, Qin X, Kong F, Chen P, Pan G. Improving cellular uptake of therapeutic entities through interaction with components of cell membrane. Drug Deliv 2019; 26:328-342. [PMID: 30905189 PMCID: PMC6442206 DOI: 10.1080/10717544.2019.1582730] [Citation(s) in RCA: 165] [Impact Index Per Article: 33.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2019] [Revised: 02/08/2019] [Accepted: 02/11/2019] [Indexed: 12/24/2022] Open
Abstract
Efficient cellular delivery of biologically active molecules is one of the key factors that affect the discovery and development of novel drugs. The plasma membrane is the first barrier that prevents direct translocation of chemic entities, and thus obstructs their efficient intracellular delivery. Generally, hydrophilic small molecule drugs are poor permeability that reduce bioavailability and thus limit the clinic application. The cellular uptake of macromolecules and drug carriers is very inefficient without external assistance. Therefore, it is desirable to develop potent delivery systems for achieving effective intracellular delivery of chemic entities. Apart from of the types of delivery strategies, the composition of the cell membrane is critical for delivery efficiency due to the fact that cellular uptake is affected by the interaction between the chemical entity and the plasma membrane. In this review, we aimed to develop a profound understanding of the interactions between delivery systems and components of the plasma membrane. For the purpose, we attempt to present a broad overview of what delivery systems can be used to enhance the intracellular delivery of poorly permeable chemic entities, and how various delivery strategies are applied according to the components of plasma membrane.
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Affiliation(s)
- Renshuai Zhang
- Key Laboratory of Flexible Electronics & Institute of Advanced Materials, Jiangsu National Synergetic Innovation Center for Advanced Materials (SICAM), Nanjing Tech University, Nanjing, P.R. China
| | - Xiaofei Qin
- Key Laboratory of Flexible Electronics & Institute of Advanced Materials, Jiangsu National Synergetic Innovation Center for Advanced Materials (SICAM), Nanjing Tech University, Nanjing, P.R. China
| | - Fandong Kong
- Key Laboratory of Biology and Genetic Resources of Tropical Crops, Ministry of Agriculture, Institute of Tropical Bioscience and Biotechnology Chinese Academy of Tropical Agriculture Sciences, Haikou, P.R. China
| | - Pengwei Chen
- Key Laboratory of Biology and Genetic Resources of Tropical Crops, Ministry of Agriculture, Institute of Tropical Bioscience and Biotechnology Chinese Academy of Tropical Agriculture Sciences, Haikou, P.R. China
| | - Guojun Pan
- School of Life Sciences, Taishan Medical University, Tai’an, P.R. China
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6
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Lobo M, Balouz V, Melli L, Carlevaro G, Cortina ME, Cámara MDLM, Cánepa GE, Carmona SJ, Altcheh J, Campetella O, Ciocchini AE, Agüero F, Mucci J, Buscaglia CA. Molecular and antigenic characterization of Trypanosoma cruzi TolT proteins. PLoS Negl Trop Dis 2019; 13:e0007245. [PMID: 30870417 PMCID: PMC6435186 DOI: 10.1371/journal.pntd.0007245] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2018] [Revised: 03/26/2019] [Accepted: 02/14/2019] [Indexed: 01/02/2023] Open
Abstract
Background TolT was originally described as a Trypanosoma cruzi molecule that accumulated on the trypomastigote flagellum bearing similarity to bacterial TolA colicins receptors. Preliminary biochemical studies indicated that TolT resolved in SDS-PAGE as ~3–5 different bands with sizes between 34 and 45 kDa, and that this heterogeneity could be ascribed to differences in polypeptide glycosylation. However, the recurrent identification of TolT-deduced peptides, and variations thereof, in trypomastigote proteomic surveys suggested an intrinsic TolT complexity, and prompted us to undertake a thorough reassessment of this antigen. Methods/Principle findings Genome mining exercises showed that TolT constitutes a larger-than-expected family of genes, with at least 12 polymorphic members in the T. cruzi CL Brener reference strain and homologs in different trypanosomes. According to structural features, TolT deduced proteins could be split into three robust groups, termed TolT-A, TolT-B, and TolT-C, all of them showing marginal sequence similarity to bacterial TolA proteins and canonical signatures of surface localization/membrane association, most of which were herein experimentally validated. Further biochemical and microscopy-based characterizations indicated that this grouping may have a functional correlate, as TolT-A, TolT-B and TolT-C molecules showed differences in their expression profile, sub-cellular distribution, post-translational modification(s) and antigenic structure. We finally used a recently developed fluorescence magnetic beads immunoassay to validate a recombinant protein spanning the central and mature region of a TolT-B deduced molecule for Chagas disease serodiagnosis. Conclusion/Significance This study unveiled an unexpected genetic and biochemical complexity within the TolT family, which could be exploited for the development of novel T. cruzi biomarkers with diagnostic/therapeutic applications. Chagas disease, caused by the protozoan Trypanosoma cruzi, is a lifelong and debilitating neglected illness of major significance in Latin America, for which no vaccine or adequate drugs are yet available. Identification of novel biomarkers able to transcend the current limits of diagnostic and/or therapeutic assessment methods hence surfaces as a main priority in Chagas disease applied research. In this framework, we herein undertook a thorough biochemical and antigenic characterization of T. cruzi TolT surface antigens. Our results unveil an unexpected complexity within this family, with at least 12 polymorphic TolT genes in the T. cruzi CL Brener reference strain genome. According to structural features, TolT deduced molecules could be split into three robust groups that show differences in their structural features, expression profile, sub-cellular distribution, post-translational modification(s) and antigenic structure. Overall, we show that TolT molecules are conspicuously expressed by both major mammal-dwelling stages of the parasite, and that they are differentially recognized by the immune system in Chagasic patients and in T. cruzi-infected mammals. Our findings are discussed in terms of the evolution and possible structural/functional roles of TolT molecules, as well as in terms of their applicability in Chagas disease serodiagnosis.
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Affiliation(s)
- Maite Lobo
- Instituto de Investigaciones Biotecnológicas “Dr Rodolfo Ugalde” (IIB-INTECh, Universidad Nacional de San Martín and CONICET), Buenos Aires, Argentina
| | - Virginia Balouz
- Instituto de Investigaciones Biotecnológicas “Dr Rodolfo Ugalde” (IIB-INTECh, Universidad Nacional de San Martín and CONICET), Buenos Aires, Argentina
| | - Luciano Melli
- Instituto de Investigaciones Biotecnológicas “Dr Rodolfo Ugalde” (IIB-INTECh, Universidad Nacional de San Martín and CONICET), Buenos Aires, Argentina
| | - Giannina Carlevaro
- Instituto de Investigaciones Biotecnológicas “Dr Rodolfo Ugalde” (IIB-INTECh, Universidad Nacional de San Martín and CONICET), Buenos Aires, Argentina
| | - María E. Cortina
- Instituto de Investigaciones Biotecnológicas “Dr Rodolfo Ugalde” (IIB-INTECh, Universidad Nacional de San Martín and CONICET), Buenos Aires, Argentina
| | - María de los Milagros Cámara
- Instituto de Investigaciones Biotecnológicas “Dr Rodolfo Ugalde” (IIB-INTECh, Universidad Nacional de San Martín and CONICET), Buenos Aires, Argentina
| | - Gaspar E. Cánepa
- Instituto de Investigaciones Biotecnológicas “Dr Rodolfo Ugalde” (IIB-INTECh, Universidad Nacional de San Martín and CONICET), Buenos Aires, Argentina
| | - Santiago J. Carmona
- Instituto de Investigaciones Biotecnológicas “Dr Rodolfo Ugalde” (IIB-INTECh, Universidad Nacional de San Martín and CONICET), Buenos Aires, Argentina
| | - Jaime Altcheh
- Servicio de Parasitología-Chagas, Hospital de Niños Ricardo Gutiérrez, Buenos Aires, Argentina
| | - Oscar Campetella
- Instituto de Investigaciones Biotecnológicas “Dr Rodolfo Ugalde” (IIB-INTECh, Universidad Nacional de San Martín and CONICET), Buenos Aires, Argentina
| | - Andrés E. Ciocchini
- Instituto de Investigaciones Biotecnológicas “Dr Rodolfo Ugalde” (IIB-INTECh, Universidad Nacional de San Martín and CONICET), Buenos Aires, Argentina
| | - Fernán Agüero
- Instituto de Investigaciones Biotecnológicas “Dr Rodolfo Ugalde” (IIB-INTECh, Universidad Nacional de San Martín and CONICET), Buenos Aires, Argentina
| | - Juan Mucci
- Instituto de Investigaciones Biotecnológicas “Dr Rodolfo Ugalde” (IIB-INTECh, Universidad Nacional de San Martín and CONICET), Buenos Aires, Argentina
- * E-mail: (JM); (CAB)
| | - Carlos A. Buscaglia
- Instituto de Investigaciones Biotecnológicas “Dr Rodolfo Ugalde” (IIB-INTECh, Universidad Nacional de San Martín and CONICET), Buenos Aires, Argentina
- * E-mail: (JM); (CAB)
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7
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Wang Y, Zhong Y, Wang Q, Yang XF, Li Z, Li H. Ratiometric Fluorescent Probe for Vicinal Dithiol-Containing Proteins in Living Cells Designed via Modulating the Intramolecular Charge Transfer–Twisted Intramolecular Charge Transfer Conversion Process. Anal Chem 2016; 88:10237-10244. [DOI: 10.1021/acs.analchem.6b02923] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Affiliation(s)
- Yuanyuan Wang
- Key
Laboratory of Synthetic and Natural Functional Molecule Chemistry
of Ministry of Education, College of Chemistry and Materials Science, Northwest University, Xi’an, Shaanxi 710127, P. R. China
| | - Yaogang Zhong
- College
of Life Sciences, Northwest University, Xi’an, Shaanxi 710069, P. R. China
| | - Qin Wang
- Key
Laboratory of Synthetic and Natural Functional Molecule Chemistry
of Ministry of Education, College of Chemistry and Materials Science, Northwest University, Xi’an, Shaanxi 710127, P. R. China
| | - Xiao-Feng Yang
- Key
Laboratory of Synthetic and Natural Functional Molecule Chemistry
of Ministry of Education, College of Chemistry and Materials Science, Northwest University, Xi’an, Shaanxi 710127, P. R. China
| | - Zheng Li
- College
of Life Sciences, Northwest University, Xi’an, Shaanxi 710069, P. R. China
| | - Hua Li
- Key
Laboratory of Synthetic and Natural Functional Molecule Chemistry
of Ministry of Education, College of Chemistry and Materials Science, Northwest University, Xi’an, Shaanxi 710127, P. R. China
- College
of Chemistry and Chemical Engineering, Xi’an Shiyou University, Xi’an, Shaanxi 710065, P. R. China
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8
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Jacquez P, Avila G, Boone K, Altiyev A, Puschhof J, Sauter R, Arigi E, Ruiz B, Peng X, Almeida I, Sherman M, Xiao C, Sun J. The Disulfide Bond Cys255-Cys279 in the Immunoglobulin-Like Domain of Anthrax Toxin Receptor 2 Is Required for Membrane Insertion of Anthrax Protective Antigen Pore. PLoS One 2015; 10:e0130832. [PMID: 26107617 PMCID: PMC4479931 DOI: 10.1371/journal.pone.0130832] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2015] [Accepted: 05/25/2015] [Indexed: 11/19/2022] Open
Abstract
Anthrax toxin receptors act as molecular clamps or switches that control anthrax toxin entry, pH-dependent pore formation, and translocation of enzymatic moieties across the endosomal membranes. We previously reported that reduction of the disulfide bonds in the immunoglobulin-like (Ig) domain of the anthrax toxin receptor 2 (ANTXR2) inhibited the function of the protective antigen (PA) pore. In the present study, the disulfide linkage in the Ig domain was identified as Cys255-Cys279 and Cys230-Cys315. Specific disulfide bond deletion mutants were achieved by replacing Cys residues with Ala residues. Deletion of the disulfide bond C255-C279, but not C230-C315, inhibited the PA pore-induced release of the fluorescence dyes from the liposomes, suggesting that C255-C279 is essential for PA pore function. Furthermore, we found that deletion of C255-C279 did not affect PA prepore-to-pore conversion, but inhibited PA pore membrane insertion by trapping the PA membrane-inserting loops in proteinaceous hydrophobic pockets. Fluorescence spectra of Trp59, a residue adjacent to the PA-binding motif in von Willebrand factor A (VWA) domain of ANTXR2, showed that deletion of C255-C279 resulted in a significant conformational change on the receptor ectodomain. The disulfide deletion-induced conformational change on the VWA domain was further confirmed by single-particle 3D reconstruction of the negatively stained PA-receptor heptameric complexes. Together, the biochemical and structural data obtained in this study provides a mechanistic insight into the role of the receptor disulfide bond C255-C279 in anthrax toxin action. Manipulation of the redox states of the receptor, specifically targeting to C255-C279, may become a novel strategy to treat anthrax.
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Affiliation(s)
- Pedro Jacquez
- Department of Biological Sciences & Border Biomedical Research Center, University of Texas at El Paso, 500 West University Avenue, El Paso, Texas, 79968, United States of America
| | - Gustavo Avila
- Department of Chemistry, University of Texas at El Paso, 500 West University Avenue, El Paso, Texas, 79968, United States of America
| | - Kyle Boone
- Bioinformatics Program of University of Texas at El Paso, 500 West University Avenue, El Paso, Texas, 79968, United States of America
| | - Agamyrat Altiyev
- Bioinformatics Program of University of Texas at El Paso, 500 West University Avenue, El Paso, Texas, 79968, United States of America
| | - Jens Puschhof
- Department of Biological Sciences & Border Biomedical Research Center, University of Texas at El Paso, 500 West University Avenue, El Paso, Texas, 79968, United States of America
| | - Roland Sauter
- Department of Biological Sciences & Border Biomedical Research Center, University of Texas at El Paso, 500 West University Avenue, El Paso, Texas, 79968, United States of America
| | - Emma Arigi
- Department of Biological Sciences & Border Biomedical Research Center, University of Texas at El Paso, 500 West University Avenue, El Paso, Texas, 79968, United States of America
| | - Blanca Ruiz
- Department of Biological Sciences & Border Biomedical Research Center, University of Texas at El Paso, 500 West University Avenue, El Paso, Texas, 79968, United States of America
| | - Xiuli Peng
- China National Key Laboratory of Agricultural Microbiology, Huazhong Agriculture University, Wuhan, 430070, P. R. China
| | - Igor Almeida
- Department of Biological Sciences & Border Biomedical Research Center, University of Texas at El Paso, 500 West University Avenue, El Paso, Texas, 79968, United States of America
| | - Michael Sherman
- Department of Biochemistry and Molecular Biology, Sealy Center for Structural Biology and Molecular Biophysics, University of Texas Medical Branch, Galveston, Texas, 77555, United States of America
| | - Chuan Xiao
- Department of Chemistry, University of Texas at El Paso, 500 West University Avenue, El Paso, Texas, 79968, United States of America
- * E-mail: (CX); (JS)
| | - Jianjun Sun
- Department of Biological Sciences & Border Biomedical Research Center, University of Texas at El Paso, 500 West University Avenue, El Paso, Texas, 79968, United States of America
- * E-mail: (CX); (JS)
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9
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Xu Y, Wu H, Huang C, Hao C, Wu B, Miao C, Chen S, Jia N. Sensitive detection of tumor cells by a new cytosensor with 3D-MWCNTs array based on vicinal-dithiol-containing proteins (VDPs). Biosens Bioelectron 2015; 66:321-6. [DOI: 10.1016/j.bios.2014.11.008] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2014] [Revised: 10/21/2014] [Accepted: 11/07/2014] [Indexed: 12/23/2022]
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10
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Perez-Jimenez R, Alonso-Caballero A, Berkovich R, Franco D, Chen MW, Richard P, Badilla CL, Fernandez JM. Probing the effect of force on HIV-1 receptor CD4. ACS NANO 2014; 8:10313-10320. [PMID: 25299596 PMCID: PMC4212800 DOI: 10.1021/nn503557w] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2014] [Accepted: 10/09/2014] [Indexed: 05/29/2023]
Abstract
Cell-surface proteins are central for the interaction of cells with their surroundings and are also associated with numerous diseases. These molecules are exposed to mechanical forces, but the exact relation between force and the functions and pathologies associated with cell-surface proteins is unclear. An important cell-surface protein is CD4, the primary receptor of HIV-1. Here we show that mechanical force activates conformational and chemical changes on CD4 that may be important during viral attachment. We have used single-molecule force spectroscopy and analysis on HIV-1 infectivity to demonstrate that the mechanical extension of CD4 occurs in a time-dependent manner and correlates with HIV-1 infectivity. We show that Ibalizumab, a monoclonal antibody that blocks HIV-1, prevents the mechanical extension of CD4 domains 1 and 2. Furthermore, we demonstrate that thiol/disulfide exchange in CD4 requires force for exposure of cryptic disulfide bonds. This mechanical perspective provides unprecedented information that can change our understanding on how viruses interact with their hosts.
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Affiliation(s)
- Raul Perez-Jimenez
- IKERBASQUE, Basque Foundation for Science, Bilbao, 48013, Spain
- CIC nanoGUNE, San Sebastian, E-20018, Spain
| | | | - Ronen Berkovich
- Department of Biological Sciences, Columbia University, New York, New York 10027, United States
| | - David Franco
- Aaron Diamond AIDS Research Center, The Rockefeller University, New York, New York 10065, United States
| | - Ming-Wei Chen
- Aaron Diamond AIDS Research Center, The Rockefeller University, New York, New York 10065, United States
| | - Patricia Richard
- Department of Biological Sciences, Columbia University, New York, New York 10027, United States
| | - Carmen L. Badilla
- Department of Biological Sciences, Columbia University, New York, New York 10027, United States
| | - Julio M. Fernandez
- Department of Biological Sciences, Columbia University, New York, New York 10027, United States
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11
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Huang C, Jia T, Tang M, Yin Q, Zhu W, Zhang C, Yang Y, Jia N, Xu Y, Qian X. Selective and Ratiometric Fluorescent Trapping and Quantification of Protein Vicinal Dithiols and in Situ Dynamic Tracing in Living Cells. J Am Chem Soc 2014; 136:14237-44. [DOI: 10.1021/ja5079656] [Citation(s) in RCA: 102] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Affiliation(s)
- Chusen Huang
- State
Key Laboratory of Bioreactor Engineering, Shanghai Key Laboratory
of Chemical Biology, School of Pharmacy, East China University of Science and Technology, 130 Meilong Road, Shanghai 200237, China
- The
Education Ministry Key Laboratory of Resource Chemistry and Shanghai
Key Laboratory of Rare Earth Functional Materials, Department of Chemistry,
College of Life and Environmental Sciences, Shanghai Normal University, 100 Guilin Road, Shanghai 200234, China
| | - Ti Jia
- The
Education Ministry Key Laboratory of Resource Chemistry and Shanghai
Key Laboratory of Rare Earth Functional Materials, Department of Chemistry,
College of Life and Environmental Sciences, Shanghai Normal University, 100 Guilin Road, Shanghai 200234, China
| | - Mengfang Tang
- State
Key Laboratory of Bioreactor Engineering, Shanghai Key Laboratory
of Chemical Biology, School of Pharmacy, East China University of Science and Technology, 130 Meilong Road, Shanghai 200237, China
| | - Qin Yin
- State
Key Laboratory of Bioreactor Engineering, Shanghai Key Laboratory
of Chemical Biology, School of Pharmacy, East China University of Science and Technology, 130 Meilong Road, Shanghai 200237, China
| | - Weiping Zhu
- State
Key Laboratory of Bioreactor Engineering, Shanghai Key Laboratory
of Chemical Biology, School of Pharmacy, East China University of Science and Technology, 130 Meilong Road, Shanghai 200237, China
| | - Chao Zhang
- State
Key Laboratory of Bioreactor Engineering, Shanghai Key Laboratory
of Chemical Biology, School of Pharmacy, East China University of Science and Technology, 130 Meilong Road, Shanghai 200237, China
| | - Yi Yang
- State
Key Laboratory of Bioreactor Engineering, Shanghai Key Laboratory
of Chemical Biology, School of Pharmacy, East China University of Science and Technology, 130 Meilong Road, Shanghai 200237, China
| | - Nengqin Jia
- The
Education Ministry Key Laboratory of Resource Chemistry and Shanghai
Key Laboratory of Rare Earth Functional Materials, Department of Chemistry,
College of Life and Environmental Sciences, Shanghai Normal University, 100 Guilin Road, Shanghai 200234, China
| | - Yufang Xu
- State
Key Laboratory of Bioreactor Engineering, Shanghai Key Laboratory
of Chemical Biology, School of Pharmacy, East China University of Science and Technology, 130 Meilong Road, Shanghai 200237, China
| | - Xuhong Qian
- State
Key Laboratory of Bioreactor Engineering, Shanghai Key Laboratory
of Chemical Biology, School of Pharmacy, East China University of Science and Technology, 130 Meilong Road, Shanghai 200237, China
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12
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Israel BA, Jiang L, Gannon SA, Thorpe C. Disulfide bond generation in mammalian blood serum: detection and purification of quiescin-sulfhydryl oxidase. Free Radic Biol Med 2014; 69:129-35. [PMID: 24468475 PMCID: PMC3960832 DOI: 10.1016/j.freeradbiomed.2014.01.020] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/16/2013] [Revised: 01/14/2014] [Accepted: 01/17/2014] [Indexed: 12/15/2022]
Abstract
A sensitive new plate-reader assay has been developed showing that adult mammalian blood serum contains circulating soluble sulfhydryl oxidase activity that can introduce disulfide bonds into reduced proteins with the reduction of oxygen to hydrogen peroxide. The activity was purified 5000-fold to >90% homogeneity from bovine serum and found by mass spectrometry to be consistent with the short isoform of quiescin-sulfhydryl oxidase 1 (QSOX1). This FAD-dependent enzyme is present at comparable activity levels in fetal and adult commercial bovine sera. Thus cell culture media that are routinely supplemented with either fetal or adult bovine sera will contain this facile catalyst of protein thiol oxidation. QSOX1 is present at approximately 25 nM in pooled normal adult human serum. Examination of the unusual kinetics of QSOX1 toward cysteine and glutathione at low micromolar concentrations suggests that circulating QSOX1 is unlikely to significantly contribute to the oxidation of these monothiols in plasma. However, the ability of QSOX1 to rapidly oxidize conformationally mobile protein thiols suggests a possible contribution to the redox status of exofacial and soluble proteins in blood plasma. Recent proteomic studies showing that plasma QSOX1 can be utilized in the diagnosis of pancreatic cancer and acute decompensated heart failure, together with the overexpression of this secreted enzyme in a number of solid tumors, suggest that the robust QSOX assay developed here may be useful in the quantitation of enzyme levels in a wide range of biological fluids.
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Affiliation(s)
- Benjamin A Israel
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE 19716, USA
| | - Lingxi Jiang
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE 19716, USA
| | - Shawn A Gannon
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE 19716, USA
| | - Colin Thorpe
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE 19716, USA.
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13
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Huang C, Yin Q, Meng J, Zhu W, Yang Y, Qian X, Xu Y. Versatile probes for the selective detection of vicinal-dithiol-containing proteins: design, synthesis, and application in living cells. Chemistry 2013; 19:7739-47. [PMID: 23592554 DOI: 10.1002/chem.201300567] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2013] [Indexed: 01/03/2023]
Abstract
Endogenous vicinal-dithiol-containing proteins (VDPs) that have two thiol groups close to each other in space play a significant importance in maintaining the cellular redox microenvironment. Approaches to identify VDPs mainly rely on monitoring the different concentration of monothiol and total thiol groups or on indirect labeling of vicinal thiols by using p-aminophenylarsenoxide (PAO). Our previous work has reported the direct labeling of VDPs with a highly selective receptor PAO analogue, which could realize fluorescence detection of VDPs directly in living cells. Herein, we developed a conjugated approach to expand detectable tags to nitrobenzoxadiazole (NBD), fluorescein, naphthalimide, and biotin for the synthesis of a series of probes. Different linkers have also been introduced toward conjugation of VTA2 with these functional tags. These synthesized flexible probes with various features will offer new tools for the potential identification and visualization of vicinal dithiols existing in different regions of VDPs in living cells. These probes are convenient tools for proteomics studies of various disease-related VDPs and for the discovery of new drug targets.
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Affiliation(s)
- Chusen Huang
- Shanghai Key Laboratory of Chemical Biology, School of Pharmacy, East China University of Science and Technology, Meilong Road 130, Shanghai, 200237, PR China
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14
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Wei W, Lampe L, Park S, Vangara BS, Waldo GS, Cabantous S, Subaran SS, Yang D, Lakatta EG, Lin L. Disulfide bonds within the C2 domain of RAGE play key roles in its dimerization and biogenesis. PLoS One 2012; 7:e50736. [PMID: 23284645 PMCID: PMC3524233 DOI: 10.1371/journal.pone.0050736] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2012] [Accepted: 10/22/2012] [Indexed: 01/11/2023] Open
Abstract
BACKGROUND The receptor for advanced glycation end products (RAGE) on the cell surface transmits inflammatory signals. A member of the immunoglobulin superfamily, RAGE possesses the V, C1, and C2 ectodomains that collectively constitute the receptor's extracellular structure. However, the molecular mechanism of RAGE biogenesis remains unclear, impeding efforts to control RAGE signaling through cellular regulation. METHODOLOGY AND RESULT: We used co-immunoprecipitation and crossing-linking to study RAGE oligomerization and found that RAGE forms dimer-based oligomers. Via non-reducing SDS-polyacrylamide gel electrophoresis and mutagenesis, we found that cysteines 259 and 301 within the C2 domain form intermolecular disulfide bonds. Using a modified tripartite split GFP complementation strategy and confocal microscopy, we also found that RAGE dimerization occurs in the endoplasmic reticulum (ER), and that RAGE mutant molecules without the double disulfide bridges are unstable, and are subjected to the ER-associated degradation. CONCLUSION Disulfide bond-mediated RAGE dimerization in the ER is the critical step of RAGE biogenesis. Without formation of intermolecular disulfide bonds in the C2 region, RAGE fails to reach cell surface. SIGNIFICANCE This is the first report of RAGE intermolecular disulfide bond.
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Affiliation(s)
- Wen Wei
- Laboratory of Cardiovascular Science, National Institute on Aging, Baltimore, Maryland, United States of America
| | - Leonie Lampe
- Laboratory of Cardiovascular Science, National Institute on Aging, Baltimore, Maryland, United States of America
| | - Sungha Park
- Laboratory of Cardiovascular Science, National Institute on Aging, Baltimore, Maryland, United States of America
| | - Bhavana S. Vangara
- Laboratory of Cardiovascular Science, National Institute on Aging, Baltimore, Maryland, United States of America
| | - Geoffrey S. Waldo
- Bioscience Division, MS-M888, Los Alamos National Laboratory, Los Alamos, New Mexico, United States of America
| | - Stephanie Cabantous
- Bioscience Division, MS-M888, Los Alamos National Laboratory, Los Alamos, New Mexico, United States of America
| | - Sarah S. Subaran
- Laboratory of Cardiovascular Science, National Institute on Aging, Baltimore, Maryland, United States of America
| | - Dongmei Yang
- Laboratory of Cardiovascular Science, National Institute on Aging, Baltimore, Maryland, United States of America
| | - Edward G. Lakatta
- Laboratory of Cardiovascular Science, National Institute on Aging, Baltimore, Maryland, United States of America
| | - Li Lin
- Laboratory of Cardiovascular Science, National Institute on Aging, Baltimore, Maryland, United States of America
- * E-mail:
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15
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Stantchev TS, Paciga M, Lankford CR, Schwartzkopff F, Broder CC, Clouse KA. Cell-type specific requirements for thiol/disulfide exchange during HIV-1 entry and infection. Retrovirology 2012. [PMID: 23206338 PMCID: PMC3526565 DOI: 10.1186/1742-4690-9-97] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
BACKGROUND The role of disulfide bond remodeling in HIV-1 infection is well described, but the process still remains incompletely characterized. At present, the data have been predominantly obtained using established cell lines and/or CXCR4-tropic laboratory-adapted virus strains. There is also ambiguity about which disulfide isomerases/reductases play a major role in HIV-1 entry, as protein disulfide isomerase (PDI) and/or thioredoxin (Trx) have emerged as the two enzymes most often implicated in this process. RESULTS We have extended our previous findings and those of others by focusing on CCR5-using HIV-1 strains and their natural targets--primary human macrophages and CD4+ T lymphocytes. We found that the nonspecific thiol/disulfide exchange inhibitor, 5,5'-dithiobis(2-nitrobenzoic acid) (DTNB), significantly reduced HIV-1 entry and infection in cell lines, human monocyte-derived macrophages (MDM), and also phytohemagglutinin (PHA)-stimulated peripheral blood mononuclear cells (PBMC). Subsequent studies were performed using specific anti-PDI or Trx monoclonal antibodies (mAb) in HIV-1 envelope pseudotyped and wild type (wt) virus infection systems. Although human donor-to-donor variability was observed as expected, Trx appeared to play a greater role than PDI in HIV-1 infection of MDM. In contrast, PDI, but not Trx, was predominantly involved in HIV-1 entry and infection of the CD4+/CCR5+ T cell line, PM-1, and PHA-stimulated primary human T lymphocytes. Intriguingly, both PDI and Trx were present on the surface of MDM, PM-1 and PHA-stimulated CD4+ T cells. However, considerably lower levels of Trx were detected on freshly isolated CD4+ lymphocytes, compared to PHA-stimulated cells. CONCLUSIONS Our findings clearly demonstrate the role of thiol/disulfide exchange in HIV-1 entry in primary T lymphocytes and MDM. They also establish a cell-type specificity regarding the involvement of particular disulfide isomerases/reductases in this process and may provide an explanation for differences among previously published studies. More importantly, from an in vivo perspective, the preferential utilization of PDI may be relevant to the HIV-1 entry and establishment of virus reservoirs in resting CD4+ cells, while the elevated levels of Trx reported in the chronic stages of HIV-1 infection may facilitate the virus entry in macrophages and help to sustain high viremia during the decline of T lymphocytes.
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Affiliation(s)
- Tzanko S Stantchev
- Laboratory of Cell Biology, Division of Monoclonal Antibodies, U.S. Food and Drug Administration, Bethesda, MD 20892, USA
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16
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Torres AG, Gait MJ. Exploiting cell surface thiols to enhance cellular uptake. Trends Biotechnol 2012; 30:185-90. [PMID: 22260747 DOI: 10.1016/j.tibtech.2011.12.002] [Citation(s) in RCA: 138] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2011] [Revised: 12/07/2011] [Accepted: 12/07/2011] [Indexed: 11/25/2022]
Abstract
Efficient cellular delivery is one of the key issues that has hampered the therapeutic development of novel synthetic biomolecules such as oligonucleotides, peptides and nanoparticles. The highly specialized cellular plasma membrane specifically internalizes compounds through tightly regulated mechanisms. It is possible to exploit these natural mechanisms of cellular uptake with rationally designed reagents. Here, we discuss how thiol groups (-SH) naturally present on the cell surface (exofacial thiols) can be used to enhance cellular association and internalization of various materials bearing thiol-reactive groups in their structure. We propose that such thiol modifications should be considered in future design of synthetic biomolecules for optimized cellular delivery.
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Affiliation(s)
- Adrian G Torres
- Medical Research Council, Laboratory of Molecular Biology, Hills Road, Cambridge CB2 0QH, UK
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17
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Click RE. Obesity, longevity, quality of life: alteration by dietary 2-mercaptoethanol. Virulence 2010; 1:509-15. [PMID: 21178502 DOI: 10.4161/viru.1.6.13803] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Previous investigations demonstrated that optimization of murine immunological reactivity in tissue culture required a sulfhydryl compound; the most effective being 2-mercaptoethanol (2-Me). Since these reports, 2-Me was found beneficial for both growth/function of other cell-types in vitro, including those of other species, and when fed orally, it impeded and/or reversed some in situ physiological changes associated with aging. More recently, thiol-containing compounds possessing oxidation-reduction potentials weaker than 2-Me were found to impart beneficial effects for many other, including human, diseases. Based on these effects, the research herein addressed the question: What consequences might dietary 2-Me impart on health and disease of mice other than those associated with aging? The main parameters monitored over the lifetime of individual animals exposed to dietary 10⁻³ M 2-Me in their drinking water were: quality of life (obesity and development of recumbent, emaciated and/or cachectic health); longevity; and appearance of tumors. Instead of anticipated toxic attributes, the following unique benefits were found; mean survival of a moderately-lived strain (A/J) was increased 40.8%, high-fat-diet obesity was curtailed in C57BL/10 mice, and a goal of aging intervention protocols, namely preventing loss of quality of life during aging (recumbent, emaciated and/or cachectic) was achieved. Various mechanisms are discussed as they pertain to these findings.
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18
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Cerutti N, Mendelow BV, Napier GB, Papathanasopoulos MA, Killick M, Khati M, Stevens W, Capovilla A. Stabilization of HIV-1 gp120-CD4 receptor complex through targeted interchain disulfide exchange. J Biol Chem 2010; 285:25743-52. [PMID: 20538591 PMCID: PMC2919137 DOI: 10.1074/jbc.m110.144121] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2010] [Revised: 06/09/2010] [Indexed: 12/17/2022] Open
Abstract
HIV-1 enters cells via interaction between the trimeric envelope (Env) glycoprotein gp120/gp41 and the host cell surface receptor molecule CD4. The requirement of CD4 for viral entry has rationalized the development of recombinant CD4-based proteins as competitive viral attachment inhibitors and immunotherapeutic agents. In this study, we describe a novel recombinant CD4 protein designed to bind gp120 through a targeted disulfide-exchange mechanism. According to structural models of the gp120-CD4 receptor complex, substitution of Ser(60) on the CD4 domain 1 alpha-helix with Cys positions a thiol in proximity of the gp120 V1/V2 loop disulfide (Cys(126)-Cys(196)), satisfying the stereochemical and geometric conditions for redox exchange between CD4 Cys(60) and gp120 Cys(126), and the consequent formation of an interchain disulfide bond. In this study, we provide experimental evidence for this effect by describing the expression, purification, refolding, receptor binding and antiviral activity analysis of a recombinant two-domain CD4 variant containing the S60C mutation (2dCD4-S60C). We show that 2dCD4-S60C binds HIV-1 gp120 with a significantly higher affinity than wild-type protein under conditions that facilitate disulfide exchange and that this translates into a corresponding increase in the efficacy of CD4-mediated viral entry inhibition. We propose that targeted redox exchange between conserved gp120 disulfides and nucleophilic moieties positioned strategically on CD4 (or CD4-like scaffolds) conceptualizes a new strategy in the development of high affinity HIV-1 Env ligands, with important implications for therapy and vaccine development. More generally, this chalcogen substitution approach provides a general means of stabilizing receptor-ligand complexes where the structural and biophysical conditions for disulfide exchange are satisfied.
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Affiliation(s)
- Nichole Cerutti
- Elevation Biotech, 8 Blackwood Avenue, Parktown 2193, Johannesburg, and
| | - Barry V. Mendelow
- From the Department of Molecular Medicine and Haematology, Faculty of Health Sciences, University of the Witwatersrand, 7 York Road, Parktown 2193, Johannesburg
| | - Grant B. Napier
- Elevation Biotech, 8 Blackwood Avenue, Parktown 2193, Johannesburg, and
| | - Maria A. Papathanasopoulos
- From the Department of Molecular Medicine and Haematology, Faculty of Health Sciences, University of the Witwatersrand, 7 York Road, Parktown 2193, Johannesburg
- Elevation Biotech, 8 Blackwood Avenue, Parktown 2193, Johannesburg, and
| | - Mark Killick
- Elevation Biotech, 8 Blackwood Avenue, Parktown 2193, Johannesburg, and
| | - Makobetsa Khati
- the Council for Scientific and Industrial Research, P. O. Box 395, Pretoria 0001, South Africa
| | - Wendy Stevens
- From the Department of Molecular Medicine and Haematology, Faculty of Health Sciences, University of the Witwatersrand, 7 York Road, Parktown 2193, Johannesburg
| | - Alexio Capovilla
- From the Department of Molecular Medicine and Haematology, Faculty of Health Sciences, University of the Witwatersrand, 7 York Road, Parktown 2193, Johannesburg
- Elevation Biotech, 8 Blackwood Avenue, Parktown 2193, Johannesburg, and
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19
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Madu IG, Belouzard S, Whittaker GR. SARS-coronavirus spike S2 domain flanked by cysteine residues C822 and C833 is important for activation of membrane fusion. Virology 2009; 393:265-71. [PMID: 19717178 PMCID: PMC3594805 DOI: 10.1016/j.virol.2009.07.038] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2009] [Revised: 05/27/2009] [Accepted: 07/30/2009] [Indexed: 01/04/2023]
Abstract
The S2 domain of the coronavirus spike (S) protein is known to be responsible for mediating membrane fusion. In addition to a well-recognized cleavage site at the S1–S2 boundary, a second proteolytic cleavage site has been identified in the severe acute respiratory syndrome coronavirus (SARS-CoV) S2 domain (R797). C-terminal to this S2 cleavage site is a conserved region flanked by cysteine residues C822 and C833. Here, we investigated the importance of this well conserved region for SARS-CoV S-mediated fusion activation. We show that the residues between C822–C833 are well conserved across all coronaviruses. Mutagenic analysis of SARS-CoV S, combined with cell–cell fusion and pseudotyped virion infectivity assays, showed a critical role for the core-conserved residues C822, D830, L831, and C833. Based on available predictive models, we propose that the conserved domain flanked by cysteines 822 and 833 forms a loop structure that interacts with components of the SARS-CoV S trimer to control the activation of membrane fusion.
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Affiliation(s)
- Ikenna G Madu
- C4127 Veterinary Medical Center, Department of Microbiology and Immunology, Cornell University, Ithaca NY 14853, USA
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20
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Abstract
There has recently been a dramatic expansion in research in the area of redox biology with systems that utilize thiols to perform redox chemistry being central to redox control. Thiol-based reactions occur in proteins involved in platelet function, including extracellular platelet proteins. The alphaIIbbeta3 fibrinogen receptor contains free thiols that are required for the activation of this receptor to a fibrinogen-binding conformation. This process is under enzymatic control, with protein disulfide isomerase playing a central role in the activation of alphaIIbbeta3. Other integrins, such as the alpha2beta1 collagen receptor on platelets, are also regulated by protein disulfide isomerase and thiol metabolism. Low molecular weight thiols that are found in blood regulate these processes by converting redox sensitive disulfide bonds to thiols and by providing the appropriate redox potential for these reactions. Additional mechanisms of redox control of platelets involve nitric oxide that inhibits platelet responses, and reactive oxygen species that potentiate platelet thrombus formation. Specific nitrosative or oxidative modifications of thiol groups in platelets may modulate platelet function. Since many biologic processes are regulated by redox reactions that involve surface thiols, the extracellular redox state can have an important influence on health and disease status and may be a target for therapeutic intervention.
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Affiliation(s)
- David W Essex
- Department of Medicine and the Sol Sherry Thrombosis Research Center, Philadelphia, Pennsylvania 19140, USA.
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21
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Auwerx J, Isacsson O, Söderlund J, Balzarini J, Johansson M, Lundberg M. Human glutaredoxin-1 catalyzes the reduction of HIV-1 gp120 and CD4 disulfides and its inhibition reduces HIV-1 replication. Int J Biochem Cell Biol 2008; 41:1269-75. [PMID: 19038358 DOI: 10.1016/j.biocel.2008.10.031] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2008] [Revised: 10/24/2008] [Accepted: 10/31/2008] [Indexed: 01/13/2023]
Abstract
Reduction of intramolecular disulfides in the HIV-1 envelope protein gp120 occurs after its binding to the CD4 receptor. Protein disulfide isomerase (PDI) catalyzes the disulfide reduction in vitro and inhibition of this enzyme blocks viral entry. PDI belongs to the thioredoxin protein superfamily that also includes human glutaredoxin-1 (Grx1). Grx1 is secreted from cells and the protein has also been found within the HIV-1 virion. We show that Grx1 efficiently catalyzes gp120, and CD4 disulfide reduction in vitro, even at low plasma levels of glutathione. Grx1 catalyzes the reduction of two disulfide bridges in gp120 in a similar manner as PDI. Purified anti-Grx1 antibodies were shown to inhibit the Grx1 activity in vitro and block HIV-1 replication in cultured peripheral blood mononuclear cells. Also, the polyanion PRO2000, that was previously shown to prevent HIV entry, inhibits the Grx1- and PDI-dependent reduction of gp120 disulfides. Our findings suggest that Grx1 activity is important for HIV-1 entry and that Grx1 and the gp120 intramolecular disulfides are novel pharmacological targets for rational drug development.
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Affiliation(s)
- Joeri Auwerx
- Division of Clinical Microbiology, Karolinska University Hospital Huddinge, F68, Karolinska Institute, Stockholm, S-14186, Sweden
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22
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Townsend DM, Tew KD. Pharmacology of a mimetic of glutathione disulfide, NOV-002. Biomed Pharmacother 2008; 63:75-8. [PMID: 18851905 DOI: 10.1016/j.biopha.2008.08.019] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2008] [Accepted: 08/26/2008] [Indexed: 10/21/2022] Open
Abstract
NOV-002 is a novel therapeutic agent in development for oncology indications used in combination with chemotherapy. Clinical trials in Russia and the USA have demonstrated clinical activity and the present focus is on non-small cell lung cancer (NSCLC) patients. The active component of the drug is oxidized glutathione (GSSG) and this imparts multiple effects upon redox pathways both at the cell surface and inside the cell. The drug induces S-glutathionylation of some proteins and impacts kinase/phosphatase regulated signaling pathways. Induction of myeloproliferation is believed to contribute to the clinical advantages provided by NOV-002 that include improved tolerance of chemotherapy and increased survival.
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Affiliation(s)
- Danyelle M Townsend
- Department of Pharmaceutical and Biomedical Sciences, Medical University of South Carolina, 173 Ashley Avenue, P.O. Box 250505, Charleston, SC 29425, USA
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23
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Townsend DM, Pazoles CJ, Tew KD. NOV-002, a mimetic of glutathione disulfide. Expert Opin Investig Drugs 2008; 17:1075-83. [PMID: 18549343 DOI: 10.1517/13543784.17.7.1075] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
BACKGROUND Oxidative signaling to modulate redox-sensitive cell functions is a heretofore unexploited approach to developing new drugs for poorly treated oncology indications, where current therapies are often only palliative and accompanied by severe toxicities. OBJECTIVE Clinical and non-clinical findings with NOV-002 (a mimetic of glutathione disulfide that represents such an approach) are reviewed and evaluated. METHODS Published data on NOV-002 along with unpublished information from the drug's sponsor were reviewed. Literature analysis also focused on protein S-glutathionylation as a regulatory mechanism, particularly in relation to cell signaling, proliferation and cytoskeletal architecture. RESULTS/CONCLUSION NOV-002 is a mechanistically novel agent with potential for ameliorating hematologic toxicity and enhancing efficacy when used in combination with standard chemotherapy to treat cancer patients.
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Affiliation(s)
- Danyelle M Townsend
- Medical University of South Carolina, Department of Pharmaceutical Sciences, 173 Ashley Avenue, PO Box 250505, Charleston, SC 29425, USA
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24
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van Anken E, Sanders RW, Liscaljet IM, Land A, Bontjer I, Tillemans S, Nabatov AA, Paxton WA, Berkhout B, Braakman I. Only five of 10 strictly conserved disulfide bonds are essential for folding and eight for function of the HIV-1 envelope glycoprotein. Mol Biol Cell 2008; 19:4298-309. [PMID: 18653472 DOI: 10.1091/mbc.e07-12-1282] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Protein folding in the endoplasmic reticulum goes hand in hand with disulfide bond formation, and disulfide bonds are considered key structural elements for a protein's folding and function. We used the HIV-1 Envelope glycoprotein to examine in detail the importance of its 10 completely conserved disulfide bonds. We systematically mutated the cysteines in its ectodomain, assayed the mutants for oxidative folding, transport, and incorporation into the virus, and tested fitness of mutant viruses. We found that the protein was remarkably tolerant toward manipulation of its disulfide-bonded structure. Five of 10 disulfide bonds were dispensable for folding. Two of these were even expendable for viral replication in cell culture, indicating that the relevance of these disulfide bonds becomes manifest only during natural infection. Our findings refine old paradigms on the importance of disulfide bonds for proteins.
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Affiliation(s)
- Eelco van Anken
- Cellular Protein Chemistry, Bijvoet Center for Biomolecular Research, Faculty of Science, Utrecht University, 3584 CH Utrecht, The Netherlands
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25
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Rees MD, Kennett EC, Whitelock JM, Davies MJ. Oxidative damage to extracellular matrix and its role in human pathologies. Free Radic Biol Med 2008; 44:1973-2001. [PMID: 18423414 DOI: 10.1016/j.freeradbiomed.2008.03.016] [Citation(s) in RCA: 145] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/21/2007] [Revised: 03/16/2008] [Accepted: 03/20/2008] [Indexed: 02/08/2023]
Abstract
The extracellular compartments of most biological tissues are significantly less well protected against oxidative damage than intracellular sites and there is considerable evidence for such compartments being subject to a greater oxidative stress and an altered redox balance. However, with some notable exceptions (e.g., plasma and lung lining fluid) oxidative damage within these compartments has been relatively neglected and is poorly understood. In particular information on the nature and consequences of damage to extracellular matrix is lacking despite the growing realization that changes in matrix structure can play a key role in the regulation of cellular adhesion, proliferation, migration, and cell signaling. Furthermore, the extracellular matrix is widely recognized as being a key site of cytokine and growth factor binding, and modification of matrix structure might be expected to alter such behavior. In this paper we review the potential sources of oxidative matrix damage, the changes that occur in matrix structure, and how this may affect cellular behavior. The role of such damage in the development and progression of inflammatory diseases is discussed.
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Affiliation(s)
- Martin D Rees
- The Heart Research Institute, 114 Pyrmont Bridge Rd, Camperdown, NSW 2050, Australia
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26
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Townsend DM, He L, Hutchens S, Garrett TE, Pazoles CJ, Tew KD. NOV-002, a glutathione disulfide mimetic, as a modulator of cellular redox balance. Cancer Res 2008; 68:2870-7. [PMID: 18413755 DOI: 10.1158/0008-5472.can-07-5957] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
NOV-002 is a novel glutathione disulfide mimetic that when administered in combination with standard chemotherapeutic regimens has resulted in increased efficacy (survival, tumor response) and improved tolerance to chemotherapy (e.g., hematologic recovery) in advanced non-small cell lung cancer patients. We show that NOV-002, which is not cytotoxic as a single agent, generated time- and concentration-dependent oxidative signals at the cell surface (reduction in protein thiols) and intracellularly [altered oxidized glutathione (GSSG) and reduced glutathione levels and ratio; increased reactive oxygen species] in the premyeloid HL-60 cell line and that this was associated with an increase in S-glutathionylation of cell proteins, particularly actin. Commensurate with these effects, NOV-002 activated p38, c-Jun-NH(2)-kinase, and extracellular signal-regulated kinase and caused a dose-dependent increase in phosphorylation of three proteins that have previously been linked with hematopoiesis, AKT, JAK2, and STAT5. The effect of NOV-002 on enzymes involved in glutathione metabolism was evaluated. Relative to oxidized glutathione, NOV-002 was an equivalent substrate for glutathione reductase and was an inhibitor of protein disulfide isomerase, one of the components of the redox-sensitive unfolded protein response pathway. These redox-stimulated cell signaling actions occurred in the context of increased HL-60 cell proliferation after treatment with NOV-002. Overall, the pleiotropic pharmacologic effects of NOV-002 can be attributed to the GSSG component of the drug, and modulation of cellular redox balance is a feature central to the mechanism of action of NOV-002. Such modulation may underlie its clinical actions, including hematologic recovery and immunostimulation in the face of chemosuppression.
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Affiliation(s)
- Danyelle M Townsend
- Department of Pharmaceutical and Biomedical Sciences, Medical University of South Carolina, Charleston, SC 29425, USA
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27
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Schwertassek U, Weingarten L, Dick TP. Identification of redox-active cell-surface proteins by mechanism-based kinetic trapping. ACTA ACUST UNITED AC 2007; 2007:pl8. [PMID: 18089859 DOI: 10.1126/stke.4172007pl8] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
A number of thiol-dependent oxidoreductases are released from cells and act on the cell surface. Correspondingly, several cell-surface processes appear to depend on catalyzed thiol-disulfide exchange, including integrin activation and the fusion of viral particles with the host membrane. Tumor cells frequently increase the abundance of secreted and cell-surface forms of particular oxidoreductases, and evidence suggests that oxidoreductases released from tumor cells promote growth and contribute to the remodeling of the cellular microenvironment. Few cell-surface or membrane proteins that are targeted by extracellular redox enzymes have been identified. One major reason for this slow progress is the highly transient nature of thiol-disulfide exchange, making its detection by conventional techniques difficult or impossible. Here we describe the application of an activity-based proteomics approach, also known as "mechanism-based kinetic trapping," to identify individual cell-surface target proteins that engage in disulfide exchange with thiol-dependent oxidoreductases. Although we have applied this approach to thioredoxin-1, it should also be applicable to other members of the thioredoxin superfamily whose activity is based on the CXXC active-site motif.
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Affiliation(s)
- Ulla Schwertassek
- Redox Regulation Research Group (A160), German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, 69120 Heidelberg, Germany
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28
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Heckler EJ, Rancy PC, Kodali VK, Thorpe C. Generating disulfides with the Quiescin-sulfhydryl oxidases. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2007; 1783:567-77. [PMID: 17980160 DOI: 10.1016/j.bbamcr.2007.10.002] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/14/2007] [Revised: 10/02/2007] [Accepted: 10/04/2007] [Indexed: 12/14/2022]
Abstract
The Quiescin-sulfhydryl oxidase (QSOX) family of flavoenzymes catalyzes the direct and facile insertion of disulfide bonds into unfolded reduced proteins with concomitant reduction of oxygen to hydrogen peroxide. This review discusses the chemical mechanism of these enzymes and the involvement of thioredoxin and flavin-binding domains in catalysis. The variability of CxxC motifs in the QSOX family is highlighted and attention is drawn to the steric factors that may promote efficient thiol/disulfide exchange during oxidative protein folding. The varied cellular location of these multi-domain sulfhydryl oxidases is reviewed and potential intracellular and extracellular roles are summarized. Finally, this review identifies important unresolved questions concerning this ancient family of sulfhydryl oxidases.
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Affiliation(s)
- Erin J Heckler
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE 19711, USA
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29
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Fenouillet E, Barbouche R, Jones IM. Cell entry by enveloped viruses: redox considerations for HIV and SARS-coronavirus. Antioxid Redox Signal 2007; 9:1009-34. [PMID: 17567241 DOI: 10.1089/ars.2007.1639] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
For enveloped viruses, genome entry into the target cell involves two major steps: virion binding to the cell-surface receptor and fusion of the virion and cell membranes. Virus-cell membrane fusion is mediated by the virus envelope complex, and its fusogenicity is the result of an active virus-cell interaction process that induces conformation changes within the envelope. For some viruses, such as influenza, exposure to an acidic milieu within the cell during the early steps of infection triggers the necessary structural changes. However, for other pathogens which are not exposed to such environmental stress, activation of fusogenicity can result from precise thiol/disulfide rearrangements mediated by either an endogenous redox autocatalytic isomerase or a cell-associated oxidoreductase. Study of the activation of HIV envelope fusogenicity has revealed new knowledge about how redox changes within a viral envelope trigger fusion. We discuss these findings and their implication for anti-HIV therapy. In addition, to compare and contrast the situation outlined for HIV with an enveloped virus that can fuse with the cell plasma membrane independent of the redox status of its envelope protein, we review parallel data obtained on SARS coronavirus entry.
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Affiliation(s)
- Emmanuel Fenouillet
- CNRS FRE2738 and Université de la Méditerranée, Faculté de Médecine, Marseille, France.
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Raturi A, Mutus B. Characterization of redox state and reductase activity of protein disulfide isomerase under different redox environments using a sensitive fluorescent assay. Free Radic Biol Med 2007; 43:62-70. [PMID: 17561094 DOI: 10.1016/j.freeradbiomed.2007.03.025] [Citation(s) in RCA: 88] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/12/2007] [Revised: 03/20/2007] [Accepted: 03/23/2007] [Indexed: 01/28/2023]
Abstract
In this study, dieosin glutathione disulfide (Di-E-GSSG) was synthesized by the reaction of eosin isothiocyanate with GSSG. Di-E-GSSG had low fluorescence which increased approximately 70-fold on reduction of its disulfide bond. The substrate was used to monitor the disulfide reductase activity of PDI. Di-E-GSSG is the most sensitive pseudo substrate for PDI reductase activity reported to date. This probe was further used as an analytical reagent to develop an end point assay for measuring the redox state of PDI. The reduction of Di-E-GSSG by reduced enzyme was studied in the absence of reducing agents and the redox state of PDI was monitored as a function of the stoichiometric changes in the amount of eosin-glutathione (EGSH) generated by the active-site dithiols of PDI. The redox state of PDI was also studied under variable [GSH]/[GSSG] ratios. The results indicate that PDI is in approximately 1/2-reduced state where the [GSH]/[GSSG] ratio is between 1:1 and 3:1, conditions similar to the lumen of endoplasmic reticulum or in the extracellular environment. On the other hand, [GSH]/[GSSG] ratios of > or =8:1, such as in cytosol, all active-site thiols would be reduced. The study was extended to utilize Di-E-GSSG to investigate the effect of variable redox ratios on the platelet surface PDI reductase activity.
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Affiliation(s)
- Arun Raturi
- Department of Chemistry and Biochemistry, University of Windsor, 401 Sunset Avenue, Windsor, Ontario, Canada N9B 3P4
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Thorpe C, Coppock DL. Generating Disulfides in Multicellular Organisms: Emerging Roles for a New Flavoprotein Family. J Biol Chem 2007; 282:13929-33. [PMID: 17353193 DOI: 10.1074/jbc.r600037200] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Affiliation(s)
- Colin Thorpe
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE 19716, USA.
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Jain S, McGinnes LW, Morrison TG. Thiol/disulfide exchange is required for membrane fusion directed by the Newcastle disease virus fusion protein. J Virol 2007; 81:2328-39. [PMID: 17151113 PMCID: PMC1865930 DOI: 10.1128/jvi.01940-06] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2006] [Accepted: 11/29/2006] [Indexed: 12/13/2022] Open
Abstract
Newcastle disease virus (NDV), an avian paramyxovirus, initiates infection with attachment of the viral hemagglutinin-neuraminidase (HN) protein to sialic acid-containing receptors, followed by fusion of viral and cell membranes, which is mediated by the fusion (F) protein. Like all class 1 viral fusion proteins, the paramyxovirus F protein is thought to undergo dramatic conformational changes upon activation. How the F protein accomplishes extensive conformational rearrangements is unclear. Since several viral fusion proteins undergo disulfide bond rearrangement during entry, we asked if similar rearrangements occur in NDV proteins during entry. We found that inhibitors of cell surface thiol/disulfide isomerase activity--5'5-dithio-bis(2-nitrobenzoic acid) (DTNB), bacitracin, and anti-protein disulfide isomerase antibody--inhibited cell-cell fusion and virus entry but had no effect on cell viability, glycoprotein surface expression, or HN protein attachment or neuraminidase activities. These inhibitors altered the conformation of surface-expressed F protein, as detected by conformation-sensitive antibodies. Using biotin maleimide (MPB), a reagent that binds to free thiols, free thiols were detected on surface-expressed F protein, but not HN protein. The inhibitors DTNB and bacitracin blocked the detection of these free thiols. Furthermore, MPB binding inhibited cell-cell fusion. Taken together, our results suggest that one or several disulfide bonds in cell surface F protein are reduced by the protein disulfide isomerase family of isomerases and that F protein exists as a mixture of oxidized and reduced forms. In the presence of HN protein, only the reduced form may proceed to refold into additional intermediates, leading to the fusion of membranes.
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Affiliation(s)
- Surbhi Jain
- Department of Molecular Genetics and Microbiology, University of Massachusetts Medical School, 55 Lake Avenue North, Worcester, MA 01655, USA
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Abstract
An emerging concept is that disulfide bonds can act as a dynamic scaffold to present mature proteins in different conformational and functional states on the cell surface. Two examples are the conversion of the receptor, integrin alphaIIbbeta3, from a low affinity to a high affinity state, and the interaction of CD4 receptor with the HIV-1 envelope glycoprotein gp120 to promote virus-cell fusion. In both of these cases there is a remodeling of the protein disulfide bonding pattern. The formation and rearrangement of disulfide bonds is modulated by a family of enzymes known as the thiol isomerases, which include protein disulfide isomerase (PDI), ERp5, ERp57, and ERp72. While these enzymes were reported originally to be restricted in location to the endoplasmic reticulum, in some cells thiol isomerases are found on the cell surface. This may indicate a wider role for these enzymes in cell function. In platelets it has been shown that reagents that react with cell surface sulfhydryl groups are capable of blocking a number of functional responses, including integrin-mediated aggregation, adhesion, and granule secretion. Furthermore, the use of function blocking antibodies to either PDI or ERp5 causes inhibition of these functional responses. This review summarizes current knowledge of the extracellular regulation of disulfide exchange and the implications of this in the regulation of cell function.
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Affiliation(s)
- Peter A Jordan
- School of Animal and Microbial Sciences, University of Reading, Whiteknights, Reading, United Kingdom
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Horváth A, Tokés S, Hartman T, Watson K, Turpin JA, Buckheit RW, Sebestyén Z, Szöllosi J, Benko I, Bardos TJ, Dunn JA, Fésüs L, Tóth FD, Aradi J. Potent inhibition of HIV-1 entry by (s4dU)35. Virology 2005; 334:214-23. [PMID: 15780871 DOI: 10.1016/j.virol.2005.01.033] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2004] [Revised: 01/04/2005] [Accepted: 01/26/2005] [Indexed: 11/24/2022]
Abstract
We have previously reported the potent in vitro HIV-1 anti-reverse transcriptase activity of a 35-mer of 4-thio-deoxyuridylate [(s(4)dU)(35)]. In efforts to define its activity in a more physiological system, studies were carried out to determine the stage of viral infection that this compound mediates its anti-viral effect. Results of the studies reported herein show that (s(4)dU)(35) is nontoxic and is capable of inhibiting both single and multi-drug resistant HIV strains (IC(50): 0.8-25.4 microg/ml) in vitro. Besides its previously reported anti-RT activity, (s(4)dU)(35) mediated its antiviral action by preventing virus attachment (IC(50): 0.002-0.003 microg/ml), and was stable in vitro and slowly degraded by DNAses. Competition studies and fluorescence resonance energy transfer (FRET) experiments indicated that (s(4)dU)(35) preferentially binds to CD4 receptors, but not to CD48. Confocal laser scanning microscopy (CLSM) studies showed that (s(4)dU)(35) did not penetrate into the cells and colocalized with cell surface thioredoxin. Our studies identify (s(4)dU)(35) as a potential novel HIV entry inhibitor that may have utility as either a systemic antiretroviral or as a preventing agent for HIV transmission.
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Affiliation(s)
- András Horváth
- Department of Biochemistry and Molecular Biology, University of Debrecen, H-4012 Debrecen, Nagyerdei krt. 98, Hungary
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Abstract
Studies on thioredoxin (Trx) and its related molecules have expanded dramatically recently. Proteins that share the similar active-site sequence, -Cys-Xxx-Yyy-Cys-, are called the Trx family, and the number of Trx family members is increasing. Trx reductase, which reduces oxidized Trx in cooperation with NADPH, has three isoforms, and peroxiredoxin, which is Trx-dependent peroxidase, has six isoforms. In addition to a role as an antioxidant, Trx and its related molecules play crucial roles in the redox regulation of signal transduction. The classical cytosolic Trx1 and truncated Trx80 are released from cells. Plasma/serum levels of Trx1 are good markers for oxidative stress. Exogenous Trx1 shows cytoprotective and antiinflammatory effects and has a good potential for clinical application. This is an update review on Trx and its related molecules.
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Affiliation(s)
- Hajime Nakamura
- Thioredoxin Project, Department of Experimental Therapeutics, Translational Research Center, Kyoto University Hospital, Kyoto, Japan.
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Sahaf B, Heydari K, Herzenberg LA, Herzenberg LA. The extracellular microenvironment plays a key role in regulating the redox status of cell surface proteins in HIV-infected subjects. Arch Biochem Biophys 2005; 434:26-32. [PMID: 15629105 DOI: 10.1016/j.abb.2004.11.015] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2004] [Revised: 09/20/2004] [Indexed: 02/06/2023]
Abstract
There is an overwhelming interest in the study of the redox status of the cell surface affecting redox signaling in the cells and also predicting the total redox status of the cells. Measuring the total surface thiols (cell surface molecule thiols, csm-SH) we have shown that the overall level of surface thiols is tightly controlled. In vitro, the total concentration of intracellular glutathione (iGSH) seems to play a regulatory role in determination of the amounts of reduced proteins on cells. In addition, short term exposure of the cell surface to glutathione disulfide (GSSG, oxidized GSH) seems to reduce the overall levels of csm-SH suggesting that the function of some cysteine containing proteins on the cell surface may be regulated by the amount of GSSG secreted from the cells or the GSSG available in the extracellular environment. Examination of peripheral blood mononuclear cells (PBMCs) from healthy or HIV-infected subjects failed to reveal a similar correlation between the intra- and extracellular thiol status of cells. Although there is a relatively wide variation between individuals in both csm-SH and iGSH there is no correlation between the iGSH and csm-SH levels measured for healthy and HIV-infected individuals. There are many reports suggesting different redox active proteins on the cell surface to be the key players in the total cell surface redox regulation. However, we suggest that the redox status of the cells is regulated through a complex and tightly regulated mechanism that needs further investigation. In the mean time, overall surface thiol measurements together with case specific protein determinations may offer the most informative approach. In this review, we discuss our own results as well as results from other laboratories to argue that the overall levels of surface thiols on the exofacial membrane are regulated primarily by redox status of the cell surface microenvironment.
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Affiliation(s)
- Bita Sahaf
- Herzenberg Laboratory, Department of Genetics, Beckman Center, B-007 Stanford University School of Medicine Stanford, CA 94304-5318, USA.
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Abstract
Cross-strand disulphides (CSDs) are unusual bonds that link adjacent strands in the same beta-sheet. Their peculiarity relates to the high potential energy stored in these bonds, both as torsional energy in the highly strained disulphide linkage and as deformation energy stored in the sheet itself. CSDs are relatively rare in protein structures but are conspicuous by their presence in proteins that are involved in cell entry. The finding that entry of botulinum neurotoxin and HIV into mammalian cells involves cleavage of CSDs suggests that the activity of other cell entry proteins may likewise involve cleavage of these bonds. We examine emerging evidence of the involvement of these unusual disulphides in cell entry events.
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Abstract
The prevailing view is that disulfide bonds have been added during evolution to enhance the stability of proteins that function in a fluctuating cellular environment. However, recent evidence indicates that disulfide bonds can be more than inert structural motifs. The function of some secreted soluble proteins and cell-surface receptors is controlled by cleavage of one or more of their disulfide bonds; this cleavage is mediated by catalysts or facilitators that are specific for their substrate.
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Affiliation(s)
- Philip J Hogg
- Centre for Vascular Research, University of New South Wales, and Department of Haematology, Prince of Wales Hospital, NSW, Australia.
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